crc/de-squeak brake conditioning treatment

amc31b · October 26, 2013

I know everything is greased. I'm going to check the pistons in the caliper and make sure they are moving too (and not loose). If she pushes the brake pedal with the truck off, about how far should the pistons move? I might just press them in a little bit and make sure they extend and make contact with the back of the pad too so I don't take a chance of popping the piston out of the caliper.

I'm replacing the guide pins as well because I could have maybe nicked them or dropped on on accident and slightly bent it.

It sounds more like it is coming from the passenger side but with brakes it's always hard to tell. And the odd part is is that they don't make a sound when cold. It was 29* this morning and they didn't make a peep until I had driven a couple miles and the brakes heated up.

It sounds to me like some part of the brake system is heating up and expanding. Expanding enough to cause 2 or more parts to touch each other and rub or vibrate, causing the squeak. That makes me think brake pad clips, caliper mounts or something along those lines.

While you are inspecting your calipers and pistons, make sure that when the brake pedal is released, the calipers fully release the pistons and give the rotors room to spin freely, quickly. My dad had a Jeep wrangler that made a ton of noise when the jeep was warm and coming to a stop. The brake fluid, caliper and rotor all getting hot made the calipers not release enough and made the brakes drag and make noise while stopping. I don't know why that happened but replacing the calipers and flushing the brake fluid fixed the problem.

I would really not think you are due for calipers but your truck is an 08. If you tow, off road or are otherwise hard on your brakes, it could very well be time for new calipers. I don't mean to send you on a wild parts chase, just throwing ideas out there. I hope this helps!

Mossyoakglock · October 26, 2013

I did make sure they were releasing. She would push the brakes while I spun the wheel and then she would release while I was still spinning and they would release quickly and spin freely. Still going to check the pistons this weekend and replace guide pins.

I don't smell any burning and the wheels are not hot like some thing is sticking.

Mossyoakglock · October 26, 2013

On a side note. I got the Akebono pads today from Akebono for the warranty and these pads are chamfered. The pads from rockauto and locally at Advance were not. Same part number and everything.

Kind of strange that one set is chamfered and one set is not. Maybe an old set before they chamfered them? Since they are chamfered I might try them and maybe they will help with some noise.

Mossyoakglock · October 27, 2013

I didn't get to check today with other stuff we already had planned so that's tomorrow but I had some random thoughts thruout the day.

If one of the calipers or caliper pistons were not pressing on the pad completely, wouldn't the truck pull to one side. I would think that if one caliper was not pressing on the pad with the full force of two pistons, it would cause the truck to pull. Correct?

There are no grooves on the rotor so nothing other than the pads are contacting it. I checked the hardware after driving and the brakes hot and all hardware is tight and nothing is loose.

Other than maybe the guide pins, when I installed the pads they were a pretty tight fit into the hardware/slides. Maybe they are catching and not making full contact with the rotor. Might file the ears down a tad for a little better fit.

amc31b · October 28, 2013

Hmm, maybe you got an older, more noisy pad design the first time. That could explain the pad's different shape and some of the noise. As far as the pads being a tight fit in the caliper brackets, I wouldn't bother filling anything. I would just return the akebono's and get your money back.

As far as the truck pulling, your pistons would have to be seriously screwed up for you to feel anything wrong with the brakes or the truck pulling to one side. When one caliper completely locks up, you will feel the truck pulling when coming to stop but slight variances are not enough to pull. Small problems with the caliper are enough to cause noisy braking though. Of course our trucks are a little more complicated when it comes to the calipers because they are dual piston design.

Again, I would just tear everything apart again, scrub every part with a wire brush and brake cleaner, inspect everything and look for problems. If you dont see any issues, lube everything up with anti-seize and sil-glyde, switch to a different brand of pads and see where that gets you. If the noise persists, get some brake quiet spray.

Mossyoakglock · October 28, 2013

Yea, I think I'm going to go with a different brand of pad and rotor. I pulled everything apart yesterday and re-lubed and everything is tight and functioning properly. Both pistons are tight in the caliper and both have even pressure on the pad and contract quickly.

I'll probably go with Raybestos AT pads and rotors since the rotor hat has the black coating to prevent rust.

It's just odd that the Advantage pads are rotors are so noisy on my truck. They are perfeclty quiet on my dad's 07 Avalanche. I don't think the design is any different on his truck vs mine. I think the only difference is that he has the spreading fingers on his hardware and mine doesn't.

I'm curious if the new pads with the chamfer are any better than the non-chamfered ones. Since I got them for free under their warranty, I might throw the new ones on and see how they do until I get the Raybestos. Can't hurt.

silveradoprime · October 30, 2013

Does your truck have drums on the rear? Just to make sure the rears aren't the culprit and your chasing a noise on the wrong end, clean and adjust your drums up, clean the pads and drum with brake cleaner, and give the adjuster a few clicks until the drum has a slight drag. The drums on the gm trucks do squeal a lil bit in cool damp weather. If it helps and goes away, you fixed it. If it don't at least you have eliminated that possibility.

Mossyoakglock · October 31, 2013

Drums in the rear but the shoes are new. Replaced them about a month ago with AC Delco Durastops. No noise out of them.

I guess I could take the drums off and check to make sure everything is good with them but I checked about a week after putting them on and everything was good.

The noise def sounds like it is coming from the front. It's more of a high pitch squeal/sqeak and metal on metal sound.

Mr_Rooney · November 2, 2013

Hi Mossy,

It is the rotors singing. You said you bought acdelco advantage rotors. A look at Rockauto lists 4 rotor options:

ACDELCO Part # 18A1705A 52.79 Advantage
ACDELCO Part # 1771014 69.79 OES
ACDELCO Part # 18A1705 59.99 Durastop
ACDELCO Part # 18A1705SD 96.79 Durastop

Those economy rotors are much more prone to causing squeal. I work with many of the brake engineers in Detroit who have taken the

time to explain to me the problems they encounter with brake noise. Rotors are the #1 cause and rotor design plus material is their solution.

The Advantage is the same design, but cheaper material. The chamfer on the pad is one of the other methods to control squeal.

I have a GMT900 2008 4x4 and recently replaced the front pads with Akebono OEM. No squeal. Even the wifes Enclave with 4 wheel disc I recently

replaced the pads with Akebono OEM. I had to replace the rear rotors and went one step up to the OES, no squeal.

You might eliminate the squeal with different pads or damping on the back of the pad. Might is the key word.

I see you are in Tennessee. I was in Knoxville last weekend visiting my son. I did go to UT, a very long time ago. Awful beating from the Tide.

Mossyoakglock · November 4, 2013

The rotors are the only thing that I can think of that are causing the noise. I did use the Advantage pads and rotors thinking they would be quiet (they make no noise on my dad's 07 Avalanche) but that has not been the case. They stop great and work well, it's just the noise, and it is getting worse every day.

Since I have the Akebono's that I got direct from them under their warranty, I'm going to pick up a set of AC Delco OES rotors and put those on. The new Akebonos are chamfered where the previous ones and the Advantage pads are not. The OES rotors are the same as what the dealer has since the part numbers match. I like the Akebonos for the fact of not having to do any break-in or bed-in cycles taking the chance of glazing either the pads or the rotors.

I'll go ahead and order some new hardware as well even though mine are new. I'll probably get the Raybestos hardware since it has a rubber backing to help with vibration/noise.

Hopefully that will stop the squeal. I don't want to use any of the disc brake quiet since the back of the bottle says to only use it with shimless pads.

CapitalTruck · November 5, 2013

Let me put in my $0.02. When I did brake work on my GMT-800 (haven't had to do it yet on the 900) the one time I used aftermarket pads I immediately noticed decreased stopping performance. That was after using Carquest blue ceramics. After that I have gone OEM all the way all the time. It should be noted that Durastops and Advantage product lines from ACDelco are NOT OEM. You need OE pads and rotors. You can get them at a store that sells ACDelco part lines. Not Advanced Auto or anything like that, but some stores market exclusively ACDelco stuff. If that doesn't work hold your nose and go to the stealer. The only time I had noise on my 800 was then the caliper pins were moving and got scored all to hell. Use good silicone caliper pin grease and you should be good in that regard. My uncle had a BMW that was always squealing. He bought some brake lube stuff that you brushed on the back of the pads, then let it set up overnight. It did the job. Might be worth a try. In summary, stick with OEM.

Mossyoakglock · November 5, 2013

Yea, that's why I'm going with the OES rotors and Akebono pads (they are the OEM supplier for the GM Trucks). They are chamfered as well so that should help some too.

The part number for the OES rotors from RockAuto is the same as the part number from the dealer. I called the dealer for their price and the part number that they gave me was the same.

CapitalTruck · November 5, 2013

They might be the OES supplier/manufacturer but they were made to GM specifications. But as others have said, do whatever works for you. I just worry about the concept that the rotors are causing the squeal. Having said that, I'm not an automotive engineer or a scientist. The replacement rotors might very well do the job with the Akebono pads.

amc31b · November 6, 2013

Mossy, It sounds like you have nailed this one down. I didn't know there were so many brake rotor choices for our trucks. Also, the brake quiet I was talking about is the kind that comes in an aerosol can and you treat the rotors with it, not the pads. Anyways, Let us know how you make out. I think you might have saved the rest of us alot of hassel when it comes times to do brakes!

Thanks for creating this thread!

Mossyoakglock · November 6, 2013

They

might be the OES supplier/manufacturer but they were made to GM

specifications. But as others have said, do whatever works for you. I

just worry about the concept that the rotors are causing the squeal.

Having said that, I'm not an automotive engineer or a scientist. The

replacement rotors might very well do the job with the Akebono pads.

When you say you worry about the concept of the rotors causing the squeal, what exactly do you mean by that?

The AC Delco OES rotors that are sold are rockauto are the exact same ones that I can get from the dealer. Part numbers match and everything. The dealer even sells the Advantage and Durastop pads and rotors. I can also understand where Mr. Rooney is coming from. The cheaper/economy rotors might be of the same design as OEM but they use a cheaper material or iron grade and don't finish/mill the rotors to a tighter tolerance.

The AC Delco OES rotors and Akebono pads should be the same as if I went to the dealer and had them do the brakes so I should be as close to stock as I can get with out going to the dealer.

AMC, I sure hope so. it seems that brakes are like oil. You hear it on here where one truck runs great and doesn't burn oil with brand x, but another truck (same year, engine, etc) does not run as well on brand x but runs much better on brand y.